Preparation of feed for fishes

PREPARATION OF FEED FOR FISHES
  • Most fish farmers and ornamental fish hobbyists make use of the commercial feed available in the market for their fishes. However, specialized feeds are often needed to feed the fishes when we conduct some experiments, when we rear difficult-to-maintain aquarium, larval or small juvenile fishes, brood fish conditioning, or administering medication to sick fish
  •  In such cases one can easily prepare the fish feed with the available ingredients.
  • Small quantities of fish feed can be prepared in the laboratory,home and in fish rearing units with commonly available ingredients and simple kitchen or laboratory equipment.
  • Nutrients essential to fish are the same as those required by most other animals.
  • The nutritional requirements of fish include
    • Proteins (amino acids)
    • Lipids (fats, oils, fatty acids)
    • Carbohydrates (sugars, starch)
    • Vitamins and minerals
  • The range of the nutrient requirement by various species of fishes and their sources

Nutrients

Range

Sources

Proteins(essential aminoacids)

32-45%

Fish meal, soybean meal, fish hydrosylate, skim milk powder, legumes, and wheat gluten

Lipids

2-45%

Oils from marine fish, vegetable oils from sunflower and linseed

Carbohydrates

10-30%

Corn flour, wheat flour

Vitamins

1-2.5%

Commercially available vitamin mix

Minerals

1-2.5%

Commercially available mineral mix

  • Apart from the above nutrient sources, many feed supplements like pigments, binding agents, antimicrobials, preservatives and attractants are commonly used in the feeds prepared for the fish feed.
  • Pigments (carotenoids) are added in the feeds prepared for ornamental fishes to enhance their colouration. Natural and synthetic pigments or carotenoids that are commercially available can be supplemented to the feed to enhance coloration in the flesh of food fish like salmon or the ornamental fishes. The pigments most frequently used supply the colors red and yellow. Astaxanthin, Spirulina, dried shrimp meal, extracts from marigold and yeast are excellent natural sources of pigments.
  • Binding agents are added to provide stability to the pellet and reduce leaching of nutrients into the water. Eg. Starch, cellulose, gelatin, gum Arabic, seaweeds products like agar, carageenin, and other alginates) are the widely used popular binding agents.
  • Antimicrobials and antioxidants are supplementd to the prepared feeds in small quantities to extend the shelf-life of fish diets and reduce the rancidity of the fats Eg. Vitamin E, BHA (butylated hydroxyanisole), ethoxyquin, Sodium and potassium salts of propionic, benzoic or sorbic acids, are commonly available antimicrobials used in the fish feed.
  • Attractants are a group of feed supplements that are added to feed to improve the feed palatability, feed intake and flavour. Amino acids like glycine and alanine, betaine (chemical) are chemoattractant that are known to stimulate strong feeding behavior in fish.
  • Dry feeds can be prepared by simply mixing of dry ingredients to form a loose mixture.
  • Mash or meals are prepared as the compressed pellets or granules. These pellets are often broken into smaller sizes known as crumbles. The pellets or granules can be made by cooking with steam or by extrusion. Depending on the feeding requirements of the fish, pellets can be made to sink or float.
  • The steps involved in the preparation of fish feed is as follows
  • Preparation of a dough-like mixture of ingredients: Mix al the finely ground ingredients , knead well by adding water and mix to get the required consistency.
  • Extruding the feed: A pasta maker, food or meat grinder with the dye of required pore size can be used to extrude the dough into noodles.
  • Preparation of pellets: The feed in the form of noodles can be cut off with a knife to the desired length or crumbled by hand, thus making pellets. The pellets can be dried in a household oven on low heat, under sun or in a forced-air oven.
  • The prepared feed can be stored in freezer bags by using a bag vacuum sealer which will extend the shelf-life of both ingredients and the feed.

 Extruded feeds

                                                         
Last modified: Thursday, 15 December 2011, 1:23 PM